RESUMEN
OBJECTIVE: In this work, the loading of nicotine onto mesoporous silicate materials and its release into a phosphate buffer solution at 37°C were investigated. METHODS: The mesoporous silicate materials designated as MCM-41 were prepared with different pore sizes via using alkyltrimethylammonium bromide surfactants with different alkyl chain lengths of carbon atoms 12, 14, and 16. The mesoporous silicate systems were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), N2-adsorption-desorption isotherms, and FT-IR spectroscopy. RESULTS: Loading of nicotine was confirmed by FTIR and thermal gravimetric analysis and was determined by High-Performance Liquid Chromatography (HPLC). CONCLUSION: A slight increase in loading capacity with increasing pore size was observed, with a loading capacity of about 17% for MCM-41(16). The release of nicotine was monitored by HPLC and was almost complete for MCM-41(14) and MCM-41(16) in 8 h.
Asunto(s)
Nicotina/química , Dióxido de Silicio/química , Dispositivos para Dejar de Fumar Tabaco , Cinética , Tamaño de la Partícula , Porosidad , Dióxido de Silicio/síntesis química , Propiedades de SuperficieRESUMEN
OBJECTIVE: To study the potential influence of selected metal ions on absorption (and hence oral bioavailability of ciprofloxacin (Cipro) in presence and absence of a competing ligand. SIGNIFICANCE: The presence of metal ions together with Cipro results in complexes exhibiting a decreased bioavailability. Attempts were made to better understand the mechanism of decreased Cipro bioavailability in the presence of metals such as calcium and ferrous ions, and a small-sized ligand citric acid (CitA). METHODS: Effect of complex size or other potential factors was studied using diffusion through synthetic membrane, permeation studies across Caco-2 cells and capillary electrophoresis. A molecular dynamics (MD) simulation study was conducted to find the arrangement and the nature of the interactions between Cipro molecules and ferrous ions. RESULTS: Cipro was shown to form complexes with metals and CitA. The presence of CitA improved permeation of Cipro through the synthetic membrane but this was not as obvious in case of Caco-2 cells. Capillary electrophoresis suggested the existence of large molecular aggregates of Cipro: metal complexes. MD simulations offered clear evidence of large size aggregates in line with the experimental findings. CitA alone significantly improved permeation of Cipro through Caco-2 cells. CONCLUSIONS: The size of the formed complexes, rather than the decrease in the solubility of formed complexes, plays a significant role in permeation (absorption) of Cipro. CitA might ameliorate the effect of co-administered metal ions on the bioavailability of Cipro.